Originally Posted by
Mozella
Yes. You don't want the gas ring to go in past the neck/shoulder junction if you can help it. You really need to decide what bullets you will optimize for. Yes, you can seat a heavy bullet deep into the case, but you'll sacrifice case volume and the gas ring will be too deep. Or, you can seat a light bullet very shallow so it's just barely holding on by it's finger nails, so to speak, so that you can get it closer to the lands if that's where it shoots best. If your particular caliber offers very light and very heavy bullets you can't really optimize for both even though you may be able to shoot both. So pick what bullets you think you'll be using for serious precision shooting and use those when you make up your dummy rounds.
Make a couple of dummy rounds with different bullets and measure the base to ogive distance. You may surprise yourself and find that a lighter bullet might just measure a bit longer than a heavy one with a different shape. I just finished reaming the throat of a new barrel (not a Shilen) and measuring CBTO distances for 8 common .223 bullets I have on hand when they're touching the lands. I used a Hornady comparator. The 77gr SMKs measured shorter than the Berger 70gr VLDs. So don't assume the heaviest bullet will be the longest.
After you finish measuring and finding the longest CBTO of your favorite bullets when they're seated at a reasonable depth, then make two dummy rounds with extra neck tension and send them to Shilen. That's what I did when I ordered my last Shilen barrel. Be sure to send two in case they drop one and it lands on it's nose. Pack them carefully.
Later on if you find that you want to use very long and heavy bullets, you can always buy a throating reamer for about a hundred and a half and extend the throat. You might also want a longer throat if testing shows that your favorite bullets prefer a really long jump. It's easy, but be careful.......... you can't go back.
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